Saturday and Sunday are the days to pick up ticket wristbands if you are buying tickets in the single-game onsale's first day next Friday, March 9. From the Cubs website:

A limited number of wristbands (10,000) will be available on a first-come, first served basis in person at Wrigley Field, starting Saturday, March 3, from 8 a.m. to 6 p.m. and Sunday, March 4, from 10 a.m. to 6 p.m. or until they are gone.

If you are in the area or are picking up a wristband, please post in the comments. I'd be interested in hearing if there are any lines, or if there appear to be few people around getting wristbands.